In a heavy Dutch oven, heat oil. Add the flour and stir and cook until the mixture darkens to a brown color, about the shade of peanut butter. Add the celery, onion, green bell pepper and garlic and saute until tender.
Whisk in chicken stock, add the ketchup, chopped tomato, and okra. Let simmer for 2 1/2 hours. About 10 minutes before serving time add cooked chicken, crabmeat and shrimp and simmer. Add lemon juice, hot sauce and Worcestershire.